Transcriptional factors are proteins that bind to specific sequences of DNA, called consensus sequences, and influence the transcription of the DNA into mRNA. Some of these factors directly participate in the transcription process by activating or inhibiting the transcription and regulate the synthesis of proteins needed by cells to function, to adapt, to respond or to differentiate. Some of these proteins have to be transcribed in a constitutive manner (essential role in cell functions) while others are only synthesised in response to specific stimuli or when the cells are for instance in pathological environment. External signals are sensed by receptors and transduced through the plasma membrane followed by cascades of enzymatic kinase reactions, resulting in a phosphorylation or dephosphorylation of the transcriptional factors which affects positively or negatively their binding to their consensus sequence.
An example of drug acting indirectly on transcriptional factor is compactin, an inhibitor of HMG CoA reductase, which leads to an up-regulation of the transcription of the LDL receptor gene, permitting the clearance of cholesterol (U.S. Pat. No. 5,563,036).